Nicotine is a well known, highly characterized alkaloid that can be isolated from the dried leaves of Nicotiana tabacum. Its numerous commercial uses include utilities such as a fumigant, an insecticide and the like. It is of therapeutically valuable in the treatment of the smoking withdrawal syndrome. This treatment is based on the fact that the administration of nicotine into the body has been readily accomplished by the method of smoking, e.g., from cigarettes, pipes or cigars. The smoker experiences a satisfactory sensation from such administration. However, smoking may be associated with health hazards not necessarily associated with administration of nicotine itself.
As a result, non-smoking methods have been devised to administer nicotine to the body. These include nicotine containing chewing gums, nicotine-impregnated dermal patches, nicotine inhalers and the like. A variety of patents have disclosed such products.
U.S. Pat. No. 4,692,462 discloses a transdermal drug delivery system having a drug reservoir composed, in part, of an ion exchange resin. The drug reservoir also contains water and a hydrophilic polymer gel. The presence of the water causes the drug to become unbound and therefore to have a disadvantageously short shelf life.
U.S. Pat. No. 3,901,248 discloses a chewable smoking substitute composition which comprises a chewing gum base and a nicotine/cation exchange resin complex dispersed in said gum base. When such composition is chewed, nicotine is released in small and reduced amounts into the mouth, within the first few minutes of chewing. The composition is marginally effective in inducing the pleasurable sensation of smoking that is typically desired from those engaged in the therapy that incorporates such chewing gum. There is no disclosure of a polyol in intimate contact with a nicotine/cation exchange resin complex, only a disclosure of the use of a minor amount of glycerol as a softener for the chewing gum base.
U.S. Pat. No. 6,586,449 claims a method for preparing a nicotine composition having a nicotine release rate of not less than 70% over a 10 minute period said method comprising (a) mixing an aqueous solution of an organic polyol with a cation exchange resin selected from the group consisting of (i)—a methacrylic, weakly acidic type of resin containing carboxylic functional groups, (ii)—a polystyrene, strongly acidic type of resin containing sulphonic functional groups, and (iii)—a polystyrene, intermediate acidic type of resin containing phosphonic functional groups, thereby forming a cation exchange resin mixture having some of its ion exchange sites partially blocked with said polyol; (b) admixing with said mixture of step (a) an aqueous solution of nicotine to form a nicotine-coated cation exchange resin admixture; and (c) removing water from said admixture to produce said nicotine composition having a nicotine release rate of not less than 70% over a 10 minute period.
This patent teaches that in carrying out the claimed process it is necessary to combine the organic polyol with the cation exchange resin to form a mixture (slurry) before adding nicotine. Thereby a cation exchange resin mixture is formed having some of its ion exchange sites partially blocked with said polyol. To the mixture thus formed is admixed an aqueous solution of nicotine, and the admixture is then dried to remove the water. According to the Examples, release rates of nicotine from dried compositions prepared in this way with different polyols were in the range of 70-77%, as compared to 65-66% without polyol, over a 10 minute period when determined according to the procedure set forth in the U.S.P. Official Monograph, Volume 25, pages 1225 and 1226.
When mixing a cation exchange resin, a polyol, and nicotine, U.S. Pat. No. 6,586,449 teaches preparation of an aqueous slurry as an intermediate which requires the removal of a considerable amount of water for isolating the nicotine delivery product comprising nicotine, a cation exchange resin and a polyol which is time consuming and requires a considerable amount of energy for evaporating the water. Furthermore, the amounts of water needed reduces the capacity of a given production plant.
It has now surprisingly been found that when mixing a cation exchange resin, a polyol, and nicotine it is not necessary to produce a slurry in order to obtain a satisfactory mixing of the constituents for obtaining a product being sufficiently homogeneous and showing the desired release properties. Thus, it has been found that it is only necessary to add a relatively small amount of water together with the other constituents, namely an amount sufficient to produce a soft and plastic mixture (a paste), in order to produce a product comprising a cation exchange resin, a polyol, and nicotine being sufficient homogeneous and showing the required release properties.